The present invention relates to the general field of the manufacturing using composite materials of rotary parts having outer flanges, particularly gas turbine casings, and more particularly retention casings for gas turbine fans for aeronautical engines.
In an aeronautical gas turbine engine, a fan casing fulfils several functions. It defines the air intake duct in the engine, bears an abradable material facing the apex of the fan blades, bears a possible structure for absorbing sound waves for acoustic processing at the motor intake and incorporates or bears a retention shield. The latter forms a trap retaining debris, such as ingested objects or fragments of damaged blades, projected by centrifugation, in order to avoid them passing through the casing and reaching other parts of the aircraft.
The production of a fan retention casing made of a composite material has already been proposed. The reader is for example referred to document EP 1,961,923 which describes the fabrication of a casing out of composite material with varying thickness, consisting of the formation of a fiber reinforcement by superimposed layers of a fiber texture and the densification of the fiber reinforcement by a matrix. According to this invention, the fiber texture is achieved by three-dimensional weaving of varying thickness and is wound in several superimposed layers on a mandrel having a central wall of profile corresponding to that of the casing to be manufactured, and two side plates with profile matching that of the outer flanges of the casing. The winding on a mandrel of a woven texture of varying thickness as described in this document makes it possible to directly provide a tubular preform having the desired profile with variable thickness.
Different closing wedges are then applied to the fiber reinforcement wound on the mandrel. The closing wedges and the mandrel thus form an injection mold into which a resin is injected before being polymerized. The injection of the resin into the injection mold can thus be carried out by an injection process of LCM (Liquid Composite Molding) type, and particularly of RTM (Resin Transfer Molding) type.
In practice, the production of the injection molds for manufacturing a composite material gas turbine casing raises the problem of guaranteeing perfect sealing of the mold. However, injection molds of the prior art have the drawback of increasing the number of sealing points. In particular, it is generally necessary to treat sealing element per element, each element of the mold having on its periphery a seal in contact with the adjoining elements of the mold. In addition, for some of these elements of the injection mold, sealing must be achieved on non-planar surfaces, which further complicates the sealing of the mold.